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Panicum dichotomiflorum — fall panicgrass

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Facts

Fall panicgrass is native to New England, where there are two varieties present. One (Panicum dichotomiflorum var. dichotomiflorum) is found throughout New England and inhabits exposed shorelines and human-disturbed areas such as roadsides and cultivated areas. The other (P. Dichotomiflorum var. puritanorum) is found in Massachusetts, New Hampshire and Rhode Island and is restricted to wet shorelines, not being found on human-disturbed habitats.

Habitat

Anthropogenic (man-made or disturbed habitats), shores of rivers or lakes

New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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Characteristics

Habitat
  • terrestrial
  • wetlands
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Leaf blade width
3–25 mm
Inflorescence branches
the flowers are attached to branches rather than to the main axis of the inflorescence
Spikelet length
1.8–3.8 mm
Glume relative length
one or both glumes are as long or longer than all of the florets
Awn on glume
the glume has no awn
One or more florets
  • there is more than one floret per spikelet
  • there is one floret per spikelet
Lemma awn length
0 mm
Leaf sheath hair type
  • there are hairs on the surface of the leaf sheath, and some of the hairs have blisters at their bases
  • there are hairs on the surface of the leaf sheath, but the hairs do not have blisters at their bases
Leaf ligule length
0.5–2 mm
Show all characteristics

  • Flowers

    Anther number
    0–3
    Awn on glume
    the glume has no awn
    Bristles below spikelets
    no
    Floret lower bract texture
    the lemma is hard and firm
    Floret number
    1–2
    Floret types within spikelet
    • NA
    • there are at least two distinct forms of florets within one spikelet
    Glume relative length
    one or both glumes are as long or longer than all of the florets
    Glume shape
    the glume is flat or curved in cross-section
    Glume veins
    • 1
    • 3
    • 5
    • 7 or more
    Inflorescence arrangement
    the spikelets are uniform
    Inflorescence axis orientation
    the inflorescence axis is straight
    Inflorescence branches
    the flowers are attached to branches rather than to the main axis of the inflorescence
    Inflorescence length
    40–400 mm
    Inflorescence type (general)
    the spikelets are borne on stalks or on branches
    Inflorescence type (specific)
    the inflorescence is branched, and the branches do NOT both grow from the same side of the plant AND look like spikes
    Lemma awn base
    NA
    Lemma awn coiled
    NA
    Lemma awn length
    0 mm
    Lemma awn number
    the lemma has no awn
    Lemma awn orientation
    NA
    Lemma cross-section
    the lemma is flat or rounded if you cut across the midpoint
    Lemma surface
    the surface of the lemma is relatively smooth (not counting any longitudinal veins or hairs)
    Lemma tip
    the lemma tip is a simple point, with or without an awn (long narrow extension ending in a point)
    Lemma vein number
    • 3
    • 5
    • 7 or more
    One or more florets
    • there is more than one floret per spikelet
    • there is one floret per spikelet
    Palea relative length
    palea is one half to fully as long as lemma
    Spikelet axis tip
    there is no extension of the spikelet axis beyond the tip of the spikelet
    Spikelet length
    1.8–3.8 mm
    Spikelet shape
    • the spikelets are elliptic (widest in the middle, tapering to the ends) in profile
    • the spikelets are ovate (egg-shaped, widest below the middle with rounded ends) in profile
    Spikelets spiny
    the spikelets do not appear spiny
    Upper glume shape
    the upper glume is widest at or below the middle

  • Growth form

    Lifespan
    the plant lives only a single year or less

  • Leaves

    Leaf auricles
    the leaves do not have auricles
    Leaf blade width
    3–25 mm
    Leaf ligule length
    0.5–2 mm
    Leaf ligule type
    the leaf ligule is in the form of a membrane with fine hairs
    Leaf sheath closed around stem
    the margins of the leaf sheath are overlapping and not fused together except in the basal half (or less)
    Leaf sheath hair type
    • there are hairs on the surface of the leaf sheath, and some of the hairs have blisters at their bases
    • there are hairs on the surface of the leaf sheath, but the hairs do not have blisters at their bases
    Leaf sheath hairs
    there are no hairs on the surface of the leaf sheath

  • Place

    Habitat
    • terrestrial
    • wetlands
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • man-made or disturbed habitats
    • shores of rivers or lakes

  • Stem, shoot, branch

    Stem spacing
    the stems grow close together in compact clusters or tufts

Wetland status

Usually occurs in wetlands, but occasionally in non-wetlands. (Wetland indicator code: FACW)

In New England

Distribution

Connecticut
present
Maine
present
Massachusetts
present
New Hampshire
present
Rhode Island
present
Vermont
present

Conservation status

Exact status definitions can vary from state to state. For details, please check with your state.

Vermont
fairly widespread (S-rank: S4)

var. dichotomiflorum

Massachusetts
widespread (S-rank: S5)

var. puritanorum

Massachusetts
fairly widespread (S-rank: S4)
New Hampshire
unrankable (S-rank: SU), Ind (code: Ind)

Subspecies and varieties

Variety dichotomiflorum is known from CT, MA, ME, NH, RI, VT. Variety puritanorum is known from MA, NH, RI; also reported from CT by Dowhan (1979), but specimens are unknown. It is more ecologically restricted, typically found on wet soil of exposed shorelines (as opposed to frequently found in human-disturbed areas in the typical subspecies).

From Flora Novae Angliae dichotomous key

3.  Panicum dichotomiflorum Michx. N

fall panicgrass.  3a. Panicum dichotomiflorum Michx. var. geniculatum (Wood) Fern.; 
3b. Panicum dichotomiflorum ssp. puritanorum (Svens.) Freckmann & Lelong • CT, MA, ME, NH, RI, VT. Exposed shorelines, wet sand, roadsides, disturbed soil, areas of cultivation.

1a.  Spikelets 2.3–3.8 mm long, narrow-ovoid, acuminate at the apex, thick and subcoriaceous; pedicels usually shorter than 3 mm … 3a. P. dichotomiflorum var. dichotomiflorum

1b.  Spikelets 1.8–2.2 mm long, ellipsoid to narrow-ovoid, acute at the apex; upper glumes and lower lemmas thin-membranaceous; pedicels commonly longer than 3 mm 
 … 3b. P. dichotomiflorum var. puritanorum Svens.

Variety dichotomiflorum is known from CT, MA, ME, NH, RI, VT. Variety puritanorum is known from MA, NH, RI; also reported from CT by Dowhan (1979), but specimens are unknown. It is more ecologically restricted, typically found on wet soil of exposed shorelines (as opposed to frequently found in human-disturbed areas in the typical subspecies).

Native to North America?

Yes and no (some introduced)

Sometimes confused with

Coleataenia longifolia:
spikelets borne on pedicels 0.5-1.5 mm long, secund, and apex of upper lemma and paleo with simple or compound papillae (vs. P. dichotomiflorum, with spikelets born on pedicels 1-6 mm long, not secund, and apex of upper lemma and palea without papillae).

Synonyms

  • Panicum dichotomiflorum Michx. var. geniculatum (Wood) Fern.

Family

Poaceae

Genus

Panicum